There are known fuel inlets for filling fuel, such as gasoline, into a fuel tank of a vehicle or the like. In general, a fuel inlet (a filler pipe) is provided with an inlet pipe to guide fuel from a fuel filler port to a fuel tank; and a breather tube to guide air containing fuel vapor in the fuel tank, which is so-called vapor, toward a distal end portion of the inlet pipe to thereby reduce an internal pressure of the fuel tank.
At a distal end portion of the inlet pipe, there are provided a thread for detachably attaching a fuel filler cap and a restriction hole for restricting a distal end position of a fuel filling gun during refueling. Specifically, a retainer separate from the inlet pipe is provided at the distal end portion of the inlet pipe, and thereby the thread and the restriction hole are provided to the inlet pipe (see Patent Document 1). The retainer is an integrally formed single component having a portion where the thread is formed and a portion where the restriction hole is formed; the retainer is formed, for example, by drawing process.
It is possible to form the thread directly to the distal end portion of the inlet pipe. In this case, however, an impact caused by a collision of a vehicle or an applied load during refueling might reduce the strengths of a thread portion and a seal portion, causing deformation thereof. Accordingly, the above-described configuration, in which the thread is formed in the retainer, is preferable. Specifically, the distal end portion of the inlet pipe (a portion forming the fuel filler port) is required to have a higher strength as compared with portions other then the distal end portion. In this respect, the configuration including the retainer separate from the inlet pipe enables achievement of a required strength by means of the retainer, and thus the inlet pipe itself is not required to have an excess strength. In contrast, the configuration, in which the thread is formed directly to the inlet pipe, requires enhanced strength of the inlet pipe itself, and thus requires the entire inlet pipe to be formed using a thick material.